The present teachings are predicated upon providing an improved disc brake system and caliper for use with vehicles. For example, the caliper may be used with almost any vehicle (e.g. car, truck, bus, train, airplane, or the like). Alternatively, the caliper may be integrated into assemblies used for manufacturing or other equipment that require a brake such as a lathe, winder for paper products or cloth, amusement park rides, or the like. However, the present invention is most suitable for use with a passenger vehicle (i.e. a car, truck, sports utility vehicle, or the like).
Generally, a braking system includes a rotor, a caliper body, a support bracket, an inboard brake pad, and an outboard brake pad located on opposing sides of the rotor. The caliper body further includes a bridge, one or more fingers, and a piston bore. The piston bore houses a piston. The bore has a bore axis that the piston moves along during a brake apply and a brake release. The piston axis may be substantially parallel to the bore axis. Preferably, the piston axis is parallel to and moves along the bore axis. The piston bore may include a fluid inlet, a closed wall, a front opening, and a cylindrical side wall that includes a seal groove located near the front opening. Typically, the fluid inlet is located in the closed wall of the piston bore so that when pressure is applied the fluid will flow into the piston bore. During a pressure apply the fluid will push the piston towards the front opening and into contact with a brake pad. However, during a pressure apply the piston may be pushed by a mechanical force instead of a fluid pressure. For example, during a brake apply, a mechanical actuator may push the piston into contact with the brake pads. Preferably, the piston is pushed by a fluid. More preferably, the piston is pushed by brake fluid.
Generally, when a brake apply is completed (i.e. released) the seal assists in moving the piston axially away from the brake pad; thus, creating an air gap. Upon a subsequent brake apply, the piston is forced into contact with the brake pad and then moves the brake pad into contact with the rotor, thus, eliminating the air gap. Moving the piston and brake pad to eliminate the air gap takes time, thus, there is a tag time between the beginning of a brake apply and when a braking force is created. This lag time lengthens stopping distance and/or running time. Examples of such braking devices are disclosed in U.S. Pat. Nos. 3,915,461 and 7,191,875; Great Britain Patent No. GB2129878; and WO00/09916 all of which are expressly incorporated herein by reference for all purposes. What is needed is a braking system that improves braking performance without decreasing fuel efficiency or increasing brake pad and rotor wear. What is needed is a braking system that minimizes or substantially eliminates air gap without adversely affecting: the life of the brake pads, the rotor, fuel economy, or a combination thereof. What is further needed is a braking system that reduces the amount of time between the beginning of a brake apply and when a braking force is created.